Process of color forming development and photographic compositions containing color forming compounds



Patented Se t. 22, 1942 PROCESS OF COLOR FORMING DEVELOP- MENT AND PHOTOGRAPHIC COMPOSI- TIONS CONTAINING COLOR FORMING COMPOUNDS George A. Dawson, Stelton, N. .J., assignor, by

mesne assignments, to E. I. du Pont de Nemours & Company, Wilmington, DeL, a corporation of Delaware No Drawing. Application September 19, 1939, Serial No. 295,684

7 Claims. 1 (Cl. 95 6) This invention relates to color photography. More particularly it relates to photographic developers and emulsions which contain novel color former compounds. Still more particularly it relates to photographic elements bearing emulsion layers which develop to form metallic silver and dyes in admixture therewith. The invention also relates to processes of producing colored images and toned photographic elements.

This invention has for an object the preparation of new photographic emulsions and developers which result in colored images of improved spectral qualities. A further object is to provide novel color-formers which couple readily upon development of silver salt images to form water insoluble immobile dyes in situ with photographic images. A still further object is to provide colorformerswhich will react with nitroso compounds upon development of photographic images. A still further object is to provide color-formers which do not affect the sensitivity of photographic emulsions, particularly gelatin silver ferrocyanide emulsions. Still other objects will be apparent fromthe hereinafter described invention.

The above and other objects are accomplished by the preparation of and use in photographic emulsion and developer solutions of alpha and gamma methyl heterocyclic nitrogen bases. These bases have thegeneralformula:

and R is vinylene or arylene. In the cases where Y is vinylene the active methyl group may be in the alpha or gamma position to the nitrogen atom.

.to a developer solution by dissolving the same in a water-soluble organic solvent or they may be directly added in finely divided form with the aid of dispersing agents such as alkylated naphthylene sulfonic acids, sulfonated oils, sulfonated higher aliphatic alcohols, etc.

The operative bases include those of the azole,

iminazole, pyridine, quinoline and indolenine.

series, including the monoand bis-oxazoles,-thiazoles,-selenazoles, and-tellurazoles. The azoles represent the preferred embodiment of the invention.

The invention will be further illustrated but is not intended to be limited by the following examples:

Examples I A small amount of a-methyl benzothiazole was dissolved in a small amount of ethanol and added to a developer solution containing N-diethyl-pphenylene-diamine. A photographic film bearing a silver ferrocyanide image was developed in the solution for five minutes. The silver. image was removed by adding the film to a ferricyanide bleaching bath. The silver salts were then removed in a plain sodium thiosulfate fixing bath and the resulting film was washed and dried. A brown (sepia) dyed image remained in place of the original ferrocyanide image. I

Similar results were obtained by substituting in a like manner other u-methyl benzoazoles. Thus a-methyl-z-chloro-benzothiazole resulted in a.

2 brown (warm sepia), a-methyl-3-methylbenzothiazole in a brownish-black, a-methyl-u-naphthothiazole in a brown, a-methyl-fl-naphthothiazole resulted in a reddish brown, a-methyl-2- phenylthiazole in a dark brown, and bis-a-methyl benzothiazole in a brown, a-methyl-selenazole in a dark brown, a-methyl-3-methylselenazole in a brown and a-methyl-finaphthoselenazole in a dark brown dyed image.

Example II A small amount of a-methyloxazole was dis-- solved in ethanol and added to a developer solution containing N-diethylp-phenylenediamine anda photographic element bearing a silver ferrocyanide image was processed therein after the manner set forth in Example I. The dyed image remaining was black. a-Methyl-3-methyl-oxazole when substituted in similar amounts gave a bluish black image and the a-methylefi-naphthoxazole in a dark reddish brown image.

Example III A small amount of p-methyl-quinoline was dissolved in methanol and incorporated in a developer solution containing N-diethyl-p-phenylenediamine and a photographic element containing a silver ferrocyanide image was processed therein in the manner described in Example I.

The dyed image was dark reddish-brown. The gamma-methyl isomer gave a reddish brown image and a-methyl-,B-naphthapyridine a brown dyed image.

Other types of silver salt images than that specifically described in the preceding examples may be used. Thus, exposed and reversed silver halide (e. g. chloride and bromide) images and bleached images may be treated.

In place of the specific bases set forth in the above examples may be substituted any base havgraphic emulsion. Furthermore, the dye components of this invention couple with diazo compounds, so that they are therefore suitable for transforming into azo dyes, followed or not by differential bleaching in the presence of silver images as is known in the art.

In place of the specific aromatic amino developing agents described in the preceding examples may be substituted various other specific agents of this type. These agents have an unsubstitut-. ed amino group which apparently enables the oxidation products formed during development to couple with-the color-forming compound. Such agents include the mono-, di-, and tri-amino aryl compounds and the compounds formed therefrom by substitution in the amino group as well as in the ring. Thus, halogen, alkyl, aralkyl and aryl groups may be present.

The preferred developing agents in the proc- I ess of dye coupling development are derivatives .of p-phenylene-diamine and particularly the group.

asymmetric dialkyl p-phenylene diamines, e. 3., p-aminodimethylaniline, p-aminodiethylaniline, p-aminodibutylaniline, etc. Other-developing agents which may be used include p-phenylenediamine itself, p-methylaminoaniline, p-ethylaminoanlline, p-aminophenol, N,N-diethyl-ophenylenediamine, chloro-p-phenylenediamine, 1,2,5-toluylenediamine, 2-amino-5-diethylaminotoluene, N-paminophenyhpiperidine, N-methyl- N-hydroxyethylp-phenylenediamine, N-butyl- N-hydroxyethyl-pphenylenediamine, fi-"y-dihydroxy-propyl-p-phenylenedlamine,. 2-amino-5- (N-B-hydroxy-ethylN-butyl) aminotoluene and its dihydrochloride, etc. These aromatic aminodeveloping agents may be used in the form of their salts, which may be either inorganic or organic. The salts are in general more stable than the free bases. As examples of suitable salts mention is made of the hydrochloride, sulfates, acetates, etc.

As many apparently widely different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that I do not limit myself to the specific embodiments hereof except as defined by the appended claims.

I claim:

1. The process which comprises developing a photographic silver salt image in the presence of a heterocyclic nitrogen base having in one of its tautomeric forms one of the following general formulae:

wherein Y is a divalent member of the group consisting of -O, --S, Se, Te-, NH- CH=CH and =C(CH3)z and R is a member of the group consisting of vinylene and arylene nuclei, with a color-coupling aromatic amino developing agent having an unsubstituted amino N wherein Y is a divalent member of the group con- CH=CH and =C(CH3)2 and R is a. member of the group consisting of vinylene and arylene nuclei, with a color-coupling aromatic diamino de-.

veloping agent having an unsubstituted amino 3. The process which comprises developing a silver ferrocyanide photographic image in the presence of a heterocyclic nitrogen base having in one of its tautomeric forms one of the following general formulae:

. l Y 4 04 1/ g: N g

wherein Y is a divalent member of the group consisting of O, --S-, --Se-, --Te--, -NH--. CH=CH and =C(CH3): and R is a. member of the group consisting of vinylene and arylene nuclei, with a color-coupling aromatic amino developing agent.

4. A developer solution which contains a heterocyclic nitrogen base having in one of its tautomeric forms one of the following general forwherein Y is a divalent member of the group consisting of --O, S,-, -Se, Te-, --NH, --CH=CH and =C(CH3)2 and R is a member of the group consisting of vinylene and arylene nuclel; with a color-coupling aromatic amino degroup.

5. A developer solution which contains an o:-

methylazole, containing a hetero atom of the oxygengroup of elements, with a color-coupling aromatic amino developing agent having an unsubstituted amino group.

6. The process which comprises color-developing a photographic silver salt image in the presence of an a-methylazole base having a hetero atom 01' the oxygen group of elements, with a color coupling aromatic amino developing agent having an unsubstituted amino group.

7. A color forming developer solution contain- .ing an aromatic amino developing agent having an unsubstituted amino group and an a-HlfithYlazole base having an hetero atom of the oxygen family of elements.

A GEORGE A. DAWSON. 

